Synthetic Underlayment vs. Felt: Making the Right Choice for Your Roof

When it comes to roofing, the underlayment is often an overlooked yet crucial component. This layer sits directly atop the roof deck and beneath the shingles, serving as a protective barrier against moisture and other environmental factors. As homeowners, understanding the differences between synthetic underlayment and felt underlayment can significantly impact the longevity and performance of your roof. In this article, we will explore the key differences, advantages, and disadvantages of both types of underlayment, helping you make an informed decision for your roofing project.

Understanding Roofing Underlayment

Roofing underlayment is a protective layer installed between the roof deck and the shingles. Its primary function is to provide an additional barrier against water infiltration, which can lead to leaks, mold, and structural damage. Underlayment also enhances the roof’s fire resistance and can improve energy efficiency by regulating temperature.

Types of Underlayment

There are two main types of roofing underlayment: synthetic and felt. Each type has its unique properties, benefits, and drawbacks.

Synthetic Underlayment: Made from advanced polymers, synthetic underlayment is designed to be lightweight, durable, and water-resistant. It typically offers superior performance in harsh weather conditions.
Felt Underlayment: This traditional option is made from asphalt-saturated paper or fiberglass. Felt underlayment is generally more affordable but may not provide the same level of durability and moisture resistance as synthetic alternatives.

Cost Considerations

When selecting roofing underlayment, cost is often a primary concern. Felt underlayment tends to be less expensive upfront, making it an attractive option for budget-conscious homeowners. However, it’s essential to consider the long-term value of your investment.

Initial Costs vs. Long-Term Value

Felt Underlayment: Typically priced around $5 per square (100 square feet), felt underlayment is a cost-effective choice for those looking to save money initially. However, its shorter lifespan (15-20 years) may lead to higher replacement costs over time.
Synthetic Underlayment: While synthetic options can range from $7 to $10 per square, their durability and longer lifespan (25-50 years) often make them a more economical choice in the long run. Investing in synthetic underlayment can save you money on repairs and replacements down the line.

Durability and Performance

Durability is a critical factor when choosing roofing underlayment. The material you select will directly impact your roof’s ability to withstand various weather conditions.

Synthetic Underlayment Advantages

Tear Resistance: Synthetic underlayment is designed to resist tearing and puncturing, making it ideal for installation in high-wind areas.
Moisture Resistance: Unlike felt, synthetic underlayment repels water, reducing the risk of mold and rot.
UV Resistance: Many synthetic products are engineered to withstand prolonged exposure to sunlight without degrading.

Felt Underlayment Limitations

Prone to Damage: Felt underlayment can tear easily during installation or under extreme weather conditions.
Moisture Absorption: Felt can absorb water, leading to potential issues with mold and mildew if not installed correctly.
Shorter Lifespan: With a lifespan of only 15-20 years, felt underlayment may require more frequent replacements.

Installation Considerations

The installation process can significantly affect the overall cost and efficiency of your roofing project. Understanding the differences in installation between synthetic and felt underlayment can help you make a more informed decision.

Ease of Installation

Synthetic Underlayment: Lightweight and available in larger rolls, synthetic underlayment is easier to handle and install. This can lead to reduced labor costs and faster project completion times.
Felt Underlayment: Heavier and available in smaller rolls, felt underlayment can be more challenging to work with, potentially increasing labor costs and installation time.

Safety and Slip Resistance

Safety is paramount during the roofing installation process. The underlayment you choose can impact the safety of the workers on your roof.

Slip Resistance

Synthetic Underlayment: Many synthetic products feature slip-resistant surfaces, providing better traction for roofers working at steep angles or in wet conditions.
Felt Underlayment: Felt can become slippery when wet, posing a safety hazard for installers.

Fire Resistance

Fire safety is another critical consideration when selecting roofing materials. The underlayment you choose can influence your roof’s overall fire rating.

Fire Ratings

Synthetic Underlayment: Typically made from materials that meet Class A fire ratings, synthetic underlayment offers superior fire resistance.
Felt Underlayment: Generally rated as Class C, felt underlayment may not provide the same level of fire protection as synthetic options.

Breathability and Ventilation

Proper ventilation is essential for maintaining a healthy attic environment. The underlayment you choose can affect your roof’s breathability.

Breathability Comparison

Synthetic Underlayment: Many synthetic products allow moisture to escape while preventing water from entering, helping to control humidity levels in your attic.
Felt Underlayment: Felt is less breathable and can trap moisture, leading to potential rot and mold issues over time.

Environmental Impact

As homeowners become more environmentally conscious, the sustainability of roofing materials is an important consideration.

Eco-Friendliness

Synthetic Underlayment: Many synthetic products are made from recycled materials and are designed to be more environmentally friendly.
Felt Underlayment: Traditional felt underlayment is often made from asphalt, which may not be as eco-friendly as synthetic alternatives.

Conclusion

Choosing between synthetic and felt underlayment ultimately depends on your specific needs, budget, and the climate in your area. While felt underlayment may be more affordable initially, synthetic underlayment offers superior durability, moisture resistance, and long-term value.

Before making a decision, consider the following:

Budget: Are you looking for a short-term solution or a long-term investment?
Climate: What are the weather conditions in your area? Will your roof be exposed to heavy rain, snow, or intense sunlight?
Installation: How important is ease of installation and safety for your roofing project?

By carefully weighing these factors, you can select the right underlayment for your roofing needs, ensuring your home remains protected for years to come. If you’re still unsure, consulting with a professional roofing contractor can provide valuable insights tailored to your specific situation.

In summary, whether you opt for synthetic underlayment or felt, understanding the differences and implications of your choice will empower you to make the best decision for your roofing project.